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ARIES Documents -- Meetings Archive

ARIES Conference Call, 4 November 1999

Documented by L. Waganer

(DOE) Dove, Wiffen
(UCSD)Baker, Mau, Miller, Raffray, Tillack, Wang
(PPPL) Jardin, Kessel, Reiersen
(GA) *
(UW) El-Guebaly, Sviatoslavsky
(FPA) *
(RPI) Steiner
(Boeing) Waganer
(INEEL) Petti
(MIT) *


The next ARIES meeting will be starting at noon, 1 December (Wednesday), and will continue through noon, 3 December (Friday). Dave Petti is concerned about his travel budget; hence, he requested a speakerphone in the meeting so that he could communicate with the team. C. Baker mentioned that the VLT is starting to use teleconferencing.

Bill Dove said that the prior hope of the Advanced Study group receiving an increased budget has disappeared. The '00 Advanced Design budget was reduced from $3M to $2.214M due to a new review by OMB (see next paragraph). An OMB budget examiner reversed a $1M increase to the recommended Systems Studies budget. However, Anne Davies has designated $400K of the FY 2000 budget to IFE studies. So our effort this year will include some IFE design activity, although drastically reduced from our original intent. The '01 budget is being finalized and will be forwarded to Congress during the next month. These budgets may be difficult for the Advanced Design group.

Charlie Baker noted that he and several others are expecting to talk to Mike Holland, OMB, to discuss the progress being made in fusion, the value of the work, and the impact of future budgets on potential benefits. Charlie was soliciting from the ARIES team specific examples of good research and developmental work to support his position on advanced design studies. The FIRE team held a meeting at SOFE, with participation of many of the ARIES team members. There is a great deal of overlap between the two teams, both in terms of personnel and the device parameters/approaches. It was suggested the FIRE team be invited to attend an ARIES project meeting to be held in the late February - March 2000 time period.

An article is requested for publication in the VLT newsletter with inputs due 29 December.

Neutron Source Study

Don Steiner noted that the Neutron Source study is progressing, but much slower than he anticipated. There are some draft sections of the final report, but other sections remain in work and undocumented. Ron Miller and Mark Tillack are cooperating to compare fusion against the principal competitor, the ATW project.

Ron Miller had previously posted a strawman 1000 MWe power producer that burned up Pu in the blanket (subcritical fissionable blanket). The next step is to develop an engineering configuration of the design. Also, Ed Cheng will assess the reactor/plant performance.

Mark Tillack is documenting the engineering performance and neutronics assessment to enable the comparison fission, fusion, and accelerators. He is frustrated by the lack of comparable technologies in the two concepts to be compared. The comparison may have to be qualitative rather than quantitative. He is planning to develop and forward to Don Steiner an outline of his final report section for comment. Ron also mentioned an ANS meeting in Long Beach that is devoted to transmutation. He noted that an ATW Roadmap document (a report to Congress) is proposing the creation of eight transmutation centers throughout the US to handle fission waste at a cost of $260B. More information can be found the DOE Office of Civilian Radioactive Waste Management (OCRWM) web site

Bill Wiffen voiced concern about the involvement of fusion with the issue of fission wastes and transmutation. Don replied that we are only doing an assessment to identify the issues and the benefits of a fusion approach as compared to the best (conventional?) transmutation approach. But the concern is duly noted.

Plasma Physics (ARIES-AT)

Steve Jardin reported that there have been no recent Physics Group calls or meetings, so there were no summary results to report.

Chuck Kessel told the group that he has been conducting studies of AT plasmas with various elongation values at a fixed aspect ratio of 4.0. Elongation has a strong influence on beta values. Plasmas with high elongation values are more prone to vertical instabilities, which require the stabilizing shell be positioned closer to the plasma. Chuck has been assuming a stabilizing shell positioned between the two outboard blanket segments (as suggested by Laila) at a distance of 0.25 x plasma minor radius. With these assumptions, he is obtaining beta values of 15% as compared to ARIES-RS values of 8% with nearly the same ARIES-RS plasma geometry. Small increases in elongation yield significant increases in beta. This would increase the power by a factor of beta2, given the same plasma geometry. However, engineering limitations begin to constrain the solution and the magnitude of the improvement. Still, it is an impressive improvement.

During the past two conference calls, TK Mau reported his progress on analyzing the current drive performance with finite plasma edge densities, on the order of 10-20%. Recently, he has been fixing the density and temperature profiles at the plasma edge per data from C. Kessel. He is analyzing the bootstrap current profile and supplementing that with edge and central plasma current drive systems. He is concerned that we have been too optimistic with the cost projections on the current drive systems. He noted that Dave Swain, of the PPPL FIRE project, has estimated these systems at $3.50/W for the first-of-a-kind experimental reactor. He mentioned that Rob Goldston inquired if we had considered CHI for the edge current drive system. But TK thought that CHI has no predictive model that would suggest this would be an attractive CD system for ARIES-AT. TK continues to investigate a system to induce plasma toroidal rotation, including off-axis, neutral beams.

Engineering (ARIES-AT)

Rene Raffray informed the group of the progress on the SiC/LiPb blanket design. This subject was recently presented in a SOFE paper. The first wall is integrated with the blanket to provide a much stronger assembly. It also allows the vertically stabilizing wall to be placed closer to the plasma, per Laila's suggestion and C. Kessel's discussion. The use of SiC allows a much higher coolant temperature, which, in turn, increases the thermal conversion efficiency from the range of 48% to around 60%. The perceived maximum structural temperature of SiC is in the range of 1000°C; but with clever engineering, the exit coolant can be in the range of 1100°C.

Rene noted that an international town meeting on SiC would be held at ORNL on 18-20 January 2000. Several people from the ARIES team will be involved in this meeting.

Igor Sviatoslavsky has been working on the attachment details of the first wall and blanket. He is also improving the flow configuration on the first wall and blanket to keep the pressure around 1.2 MPa. He is also investigating the design approach for the divertor—tungsten surface with helium or LiPb coolant. He noted that he is now using the lower SiC thermal coefficient data for thermal analyses.

Laila affirmed the tungsten vertical stabilizing shell would be placed outboard, between the two high temperature blanket elements. This would be approximately 30 cm from the front surface of the first wall. The thickness of the tungsten shell would be 3 cm. With the tungsten shell in place, the blanket can meet the breeding requirement . The 3 cm thick shell degrades the breeding of the parts of the blanket behind it by ~30%. The decay heat from this W shell is minimal due to the small volume. Igor is investigating a cooling arrangement and support system. In response to a question from Dave Petti, Ron Miller, Laila said the high temperature shields are cooled with LiPb and the low temperature shields and vacuum vessel are cooled with water (no He coolant is considered for the IB and OB components).

Mark Tillack reported the ARIES-AT design effort, including CAD, is being accomplished in a distributed manner throughout the team. PPPL is doing the magnets, and UCSD will be in charge of the CAD design integration. Ron noted that the team should start with the ARIES-RS maintenance scheme and see if it can be adapted to the AT configuration. Edge physics requirements are needed to establish machine size and configuration requirements. Can we justify radiating 50% of the transport heat load? Need to develop a radiation transport model for the core and divertor region.

Dave Petti has been looking at accident scenarios in addition to the normal LOCA and LOFA for ARIES-RS and ARIES-AT designs. Different initiation events lead to differing scenarios.

Systems Analyses

Ron reminded us that he published the AT strawmen for both 1 GW and 1.5 GW sizes. These cases do not reflect the most current and highest beta data sets being discussed. The current strawmen utilized available EQDISK files. Beta was reduced from 7.1% to 6.4%, consistent with the "operate at 90% beta" groundrule. Bootstrap current was 91%. RF current was 1.7 MA? Neutron multiplication was 1.1. Neutron wall life was set at 15 MW•y/m2, although Laila is recommending 18.5 MW•y/m2. There was some question as to the optimum Li enrichment to balance the blanket thickness against the extra enrichment cost. The validity of the enrichment cost is being investigated.

Leslie Bromberg has provided input to Ron on the cost and performance scaling of the high temperature superconductor coils. The peak field capability is currently not being fully utilized. Ron noted that the plant factor is being reviewed for possible updating. INEEL is concentrating on the reliability portion of this factor.

There was a general feeling that we should move away from the use of the LSA rating scheme. It was suggested that with the most current ARIES-AT strawmen, we should report the economics consistent with the LSA = 1 rating. Most previous ARIES power plants were reported at an LSA of 2. We all agreed that this LSA scheme is an expedient factor to account for the economic impact of varying levels of inherent safety and we would like to get rid of it. But at present, there does not seem to be a better methodology to replace it. No action recommended.

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